Published August 2025 | Version Published
Journal Article Open

BASS. XLIV. Morphological preferences of local hard X-ray selected AGNs

  • 1. ROR icon Pontificia Universidad Católica de Chile
  • 2. ROR icon University of Tarapacá
  • 3. ROR icon University of Naples Federico II
  • 4. ROR icon Astronomical Observatory of Capodimonte
  • 5. ROR icon Millennium Institute of Astrophysics
  • 6. ROR icon Eureka Scientific
  • 7. ROR icon Yonsei University
  • 8. ROR icon University of Liège
  • 9. ROR icon Ghent University
  • 10. ROR icon Korea Astronomy and Space Science Institute
  • 11. ROR icon Diego Portales University
  • 12. ROR icon Peking University
  • 13. ROR icon Roma Tre University
  • 14. ROR icon Astronomical Observatory of Rome
  • 15. ROR icon Federico Santa María Technical University
  • 16. ROR icon Texas A&M University
  • 17. ROR icon Leiden University
  • 18. ROR icon California Institute of Technology
  • 19. ROR icon Leibniz Institute for Astrophysics Potsdam
  • 20. ROR icon Jet Propulsion Lab
  • 21. ROR icon Tel Aviv University
  • 22. ROR icon Yale University

Abstract

We present detailed morphological classifications for the hosts of 1189 hard X-ray selected (14–195 keV) active galactic nuclei (AGNs) from the Swift-BAT 105-month catalog as part of the BAT AGN Spectroscopic Survey (BASS). BASS provides a powerful all-sky census of nearby AGNs, minimizing obscuration biases and providing a robust dataset for studying AGN-host galaxy connections. Classifications are based on a volunteer-based visual inspection workflow on the Zooniverse platform, adapted from the Galaxy Zoo DECaLS (GZD) project. Dual-contrast grz color composite images, generated from public surveys (e.g., NOAO Legacy Survey, Pan-STARRS, SDSS) and dedicated observations enabled key morphological features to be identified. Our analysis reveals that, with respect to a control sample of inactive galaxies, BASS AGN hosts show a deficiency of smooth elliptical galaxies (∼70%) and spiral galaxies with prominent arms (∼80%), while displaying an excess of mergers or disturbed systems (∼400%), and disk galaxies without a spiral structure (∼300%). These trends are found after controlling for redshift and i-band magnitude, which suggests a preference for AGN activity in gas-rich, dynamically disturbed environments or transitional disk systems. We also find a higher bar fraction among AGN hosts than in a control sample (∼50% vs. ∼30%). We further explore the relationships between AGN properties (e.g., X-ray luminosity, black hole mass, and Eddington ratio) and host morphology, and find that high-luminosity and high-accretion AGNs preferentially reside in smooth or point-like hosts. At the same time, lower-luminosity AGNs are more common in disk galaxies. These results underscore the importance of morphological studies in understanding the fueling and feedback mechanisms that drive AGN activity and their role in galaxy evolution. Our dataset provides a valuable benchmark for future multiwavelength surveys (e.g. LSST, Roman, and Euclid) and automated morphological classification efforts.

Copyright and License

© The Authors 2025. Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Acknowledgement

We kindly thank the referee for the thorough reading of the manuscript and subsequent suggestions. We gratefully acknowledge funding from ANID - Millennium Science Initiative - AIM23-0001 and ICN12_009 (FEB), CATA-BASAL - FB210003 (FEB), and FONDECYT Regular – 1241005 (MPT, FEB). DD acknowledges PON R&I 2021, CUP E65F21002880003, and Fondi di Ricerca di Ateneo (FRA), linea C, progetto TORNADO. CF acknowledges support from FONDECYT Postdoctoral grant – 3220751. IMC acknowledges support from FONDECYT Postdoctoral grant 3230653. AC and JK acknowledge support by the National Research Foundation of Korea (NRF), No. RS-2022-NR070872 and RS-2022-NR069020. KO acknowledges support from the Korea Astronomy and Space Science Institute under the R&D program (Project No. 2025-1-831-01), supervised by the Korea AeroSpace Administration, and the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (RS-2025-00553982). This publication uses data generated via the Zooniverse.org platform, development of which is funded by generous support, including a Global Impact Award from Google, and by a grant from the Alfred P. Sloan Foundation. The Legacy Surveys consist of three individual and complementary projects: the Dark Energy Camera Legacy Survey (DECaLS; Proposal ID #2014B-0404; PIs: David Schlegel and Arjun Dey), the Beijing-Arizona Sky Survey (BASS; NOAO Prop. ID #2015A-0801; PIs: Zhou Xu and Xiaohui Fan), and the Mayall z-band Legacy Survey (MzLS; Prop. ID #2016A-0453; PI: Arjun Dey). DECaLS, BASS and MzLS together include data obtained, respectively, at the Blanco telescope, Cerro Tololo Inter-American Observatory, NSF’s NOIRLab; the Bok telescope, Steward Observatory, University of Arizona; and the Mayall telescope, Kitt Peak National Observatory, NOIRLab. Pipeline processing and analyses of the data were supported by NOIRLab and the Lawrence Berkeley National Laboratory (LBNL). The Legacy Surveys project is honored to be permitted to conduct astronomical research on Iolkam Du’ag (Kitt Peak), a mountain with particular significance to the Tohono O’odham Nation. NOIRLab is operated by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation. LBNL is managed by the Regents of the University of California under contract to the U.S. Department of Energy. This project used data obtained with the Dark Energy Camera (DECam), which was constructed by the Dark Energy Survey (DES) collaboration. Funding for the DES Projects has been provided by the U.S. Department of Energy, the U.S. National Science Foundation, the Ministry of Science and Education of Spain, the Science and Technology Facilities Council of the United Kingdom, the Higher Education Funding Council for England, the National Center for Supercomputing Applications at the University of Illinois at Urbana-Champaign, the Kavli Institute of Cosmological Physics at the University of Chicago, Center for Cosmology and Astro-Particle Physics at the Ohio State University, the Mitchell Institute for Fundamental Physics and Astronomy at Texas A&M University, Financiadora de Estudos e Projetos, Fundacao Carlos Chagas Filho de Amparo, Financiadora de Estudos e Projetos, Fundacao Carlos Chagas Filho de Amparo a Pesquisa do Estado do Rio de Janeiro, Conselho Nacional de Desenvolvimento Cientifico e Tecnologico and the Ministerio da Ciencia, Tecnologia e Inovacao, the Deutsche Forschungsgemeinschaft and the Collaborating Institutions in the Dark Energy Survey. The Collaborating Institutions are Argonne National Laboratory, the University of California at Santa Cruz, the University of Cambridge, Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas-Madrid, the University of Chicago, University College London, the DES-Brazil Consortium, the University of Edinburgh, the Eidgenossische Technische Hochschule (ETH) Zurich, Fermi National Accelerator Laboratory, the University of Illinois at Urbana-Champaign, the Institut de Ciencies de l’Espai (IEEC/CSIC), the Institut de Fisica d’Altes Energies, Lawrence Berkeley National Laboratory, the Ludwig Maximilians Universitat Munchen and the associated Excellence Cluster Universe, the University of Michigan, NSF’s NOIRLab, the University of Nottingham, the Ohio State University, the University of Pennsylvania, the University of Portsmouth, SLAC National Accelerator Laboratory, Stanford University, the University of Sussex, and Texas A&M University. BASS is a key project of the Telescope Access Program (TAP), which has been funded by the National Astronomical Observatories of China, the Chinese Academy of Sciences (the Strategic Priority Research Program “The Emergence of Cosmological Structures” Grant # XDB09000000), and the Special Fund for Astronomy from the Ministry of Finance. The BASS is also supported by the External Cooperation Program of Chinese Academy of Sciences (Grant # 114A11KYSB20160057), and Chinese National Natural Science Foundation (Grant # 12120101003, # 11433005). The Legacy Survey team makes use of data products from the Near-Earth Object Wide-field Infrared Survey Explorer (NEOWISE), which is a project of the Jet Propulsion Laboratory/California Institute of Technology. NEOWISE is funded by the National Aeronautics and Space Administration. The Legacy Surveys imaging of the DESI footprint is supported by the Director, Office of Science, Office of High Energy Physics of the U.S. Department of Energy under Contract No. DE-AC02-05CH1123, by the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility under the same contract; and by the U.S. National Science Foundation, Division of Astronomical Sciences under Contract No. AST-0950945 to NOAO. The Pan-STARRS1 Surveys (PS1) and the PS1 public science archive have been made possible through contributions by the Institute for Astronomy, the University of Hawaii, the Pan-STARRS Project Office, the Max-Planck Society and its participating institutes, the Max Planck Institute for Astronomy, Heidelberg and the Max Planck Institute for Extraterrestrial Physics, Garching, The Johns Hopkins University, Durham University, the University of Edinburgh, the Queen’s University Belfast, the Harvard-Smithsonian Center for Astrophysics, the Las Cumbres Observatory Global Telescope Network Incorporated, the National Central University of Taiwan, the Space Telescope Science Institute, the National Aeronautics and Space Administration under Grant No. NNX08AR22G issued through the Planetary Science Division of the NASA Science Mission Directorate, the National Science Foundation Grant No. AST-1238877, the University of Maryland, Eotvos Lorand University (ELTE), the Los Alamos National Laboratory, and the Gordon and Betty Moore Foundation. This research uses services or data provided by the Astro Data Lab, which is part of the Community Science and Data Center (CSDC) Program of NSF NOIRLab. NOIRLab is operated by the Association of Universities for Research in Astronomy (AURA), Inc. under a cooperative agreement with the U.S. National Science Foundation.

Data Availability

Full Table 4 is available at the CDS via https://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/700/A111

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Additional details

Related works

Is new version of
Discussion Paper: arXiv:2506.21800 (arXiv)
Is supplemented by
Dataset: https://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/700/A111 (URL)

Funding

Agencia Nacional de Investigación y Desarrollo
AIM23-0001
Agencia Nacional de Investigación y Desarrollo
ICN12_009
Agencia Nacional de Investigación y Desarrollo
FB210003
Fondo Nacional de Desarrollo Científico y Tecnológico
1241005
University of Ferrara
PON R&I 2021 CUP E65F21002880003
Fondo Nacional de Desarrollo Científico y Tecnológico
3220751
Fondo Nacional de Desarrollo Científico y Tecnológico
3230653
National Research Foundation of Korea
RS-2022-NR070872
National Research Foundation of Korea
RS-2022-NR069020
Korea Astronomy and Space Science Institute
2025-1-831-01
National Research Foundation of Korea
RS-2025-00553982
Alfred P. Sloan Foundation
Chinese Academy of Sciences
XDB09000000
Ministry of Finance of the People's Republic of China
Chinese Academy of Sciences
114A11KYSB20160057
National Natural Science Foundation of China
12120101003
National Natural Science Foundation of China
11433005
National Aeronautics and Space Administration
NNX08AR22G
United States Department of Energy
DE-AC02-05CH1123
National Science Foundation
AST-0950945
National Science Foundation
AST-1238877

Dates

Accepted
2025-06-12
Available
2025-08-11
Published online

Caltech Custom Metadata

Caltech groups
Astronomy Department, Division of Physics, Mathematics and Astronomy (PMA)
Publication Status
Published